UJM: Yes, Otzar haChochma has many more seforim, but their “Bnei Torah” edition specifically excludes works from certain authors, generally those that are Religious Zionist or academic. That’s what differentiates it and that’s why it’s called the “Bnei Torah” edition — it censors out works that do not match yeshivishe expectations.
As I wrote above,
‘As mentioned above, very different products.
Aside from what’s already mentioned, Bar Ilan’s library includes Encyclopedia Talmudit, tries to use the most accurate version of all its texts, and includes important texts by Rabbonim and poskim from the Dati Leumi world, including journal articles, teshuvos, etc.
Those texts do not appear in the “Bnei Torah” version of Otzar, which deletes works from outside the charedi world.
If you would like to learn about Shevi’is, for instance, and don’t want to be exposed to the works that Rav Shlomo Zalman Auerbach considered the most essential ever written on that topic, quoting them on nearly every page of his own work (Rav Kook’s seforim on Shevi’is), then Otzar haChochma Bnei Torah Edition is for you.
If you would like to see what Rav Shlomo Zalman learned and what he thought was essential, then you’ll need Bar Ilan.”